On another occasion, Treadwell says he executed a villager he believed was a Viet Cong responsible for setting booby traps. “I thought he was VC,” he says. “I made that judgment. We’ll never know. I terminated his life. I don’t know if I was more pissed off at his attitude, but I labeled him a VC and fucking popped him.”

He’s still tormented by the incident. “I saw myself as crossing the line. That’s what haunts me. My government is telling me to help stop the spread of communism, and here I am committing a frigging murder. I went out and hunted this guy down. There’s no getting rid of it, and I don’t deserve to get it off my conscience.”

Six days after returning home, Treadwell spent the evening drinking a six-pack of beer in the driveway of his parents’ house in Whittier. A neighbor who didn’t recognize him called the police; a plainclothes burglary detective took the call. Treadwell remembers only that someone stepped out of the bushes on the side of the yard and startled him, so he backed away to the house.

John Wylie Needham is accused of murdering his girlfriend just months after returning from Iraq

As Treadwell opened the door, the officer shot him through the shoulder. Oblivious to the pain, he calmly walked inside, retrieved a shotgun and .45-caliber pistol from his dad’s bedroom, and began firing out the front door. Fortunately, he didn’t hit anybody, and a judge sentenced Treadwell, then 20 years old, to three and a half years in a youth-authority prison. He received an undesirable discharge from the Marines.

After getting out of prison, Treadwell worked construction jobs, and then built a career restoring and renovating restaurants. He married and had kids, but his wife left him in 1995 when he tried to talk to her about the war. “I was having nightmares and trying to tell her about them, and she just said, ‘Deal with it,’” he says. “She left me a few weeks before the rent was due, and I’ve been homeless ever since.”

He has bounced in and out of shelters but says he spends most of his nights on the streets, staying at one of about 20 locations he’s found where he can sleep in quiet. He doesn’t drink or use drugs and has only been to jail once (for fighting with a drunken homeless person who insisted on pressing charges). Occasionally, he has a confrontation with a cop, and he’s learned to recognize his propensity to react angrily when confronted by someone in uniform.

“One of my triggers is cops, obviously,” he says. “I have tested probably two dozen cops over the years who had their guns out. ‘Put it right here, motherfucker! Look in my eyes: Do I look intimidated?’”

Treadwell, now 58, hasn’t been to a VA hospital since January 2007, when he learned that his benefits were being taken away because of his less-than-honorable discharge. “They must have figured out I’d react adversely because I turned around, and there were two federal cops standing by. They said I was no longer eligible, and I was in there that day to see my frigging psychologist. They are just getting overwhelmed with new guys.”

Although he no longer visits the VA hospital for treatment, Treadwell visits the OC Veterans Center nearly every day, sometimes to participate in group therapy, but more often just to use the Internet or check e-mail.

“It’s helped me to be able to talk to other people and listen to other people and get some feedback on how I see things,” he says. “The other day in my group, somebody said, ‘We’d really like to see things get better for you.’ I told him that I’m doing nothing but preparing to die. I’m not suicidal. I’ve just lost hope.”